[LeetCode] 193. Valid Phone Numbers

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Problem

Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.

You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)

You may also assume each line in the text file must not contain leading or trailing white spaces.

Example:

Assume that file.txt has the following content:

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987-123-4567
123 456 7890
(123) 456-7890

Your script should output the following valid phone numbers:

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987-123-4567
(123) 456-7890

Explanation

  1. We can use grep -E or awk to print the matched regular expression string.

Solution

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# Read from the file file.txt and output all valid phone numbers to stdout.
grep -E '^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$' file.txt
# awk '/^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$/' file.txt